30 research outputs found
Biological responses of white sea bream (Diplodus sargus, Linnaeus 1758) and sardine (Sardine pilchardus, Walbaum 1792) exposed to heavy metal contaminated water
No full textThe aim of the present work was to assess, by rapid approach, the detoxification capacity and the genotoxicity caused by exposure of
some marine fish to polluted waters. The fish species selected for the study: White sea bream (Diplodus sargus, Linnaeus 1758) and
sardine (Sardine pilchardus, Walbaum 1792) were collected from different sites of Alexandria, El-Max bay and Bahary, in Egypt. Results
of heavy metals analysis in sediment were: Al>Fe>Cr>Pb>Hg>Cd. Concerning detoxification analysis, fish collected from El-Max bay
encounter the highest liver enzyme activity of Glutathione S-Transferase. Also, genotoxicity was evaluated in liver, gills and muscle of fishes
collected and the results indicated that fish collected from El-Max bay has the highest levels of comets (DNA damage) when compared
to the other sites selected as reference. It can be concluded from our results that the different tissues examined have alteration of level
of detossification and comets as result of different degree of oxidative pollution insult. These biological responses may be considered for
rapid extimation of food oxidative damage as well as for environmental quality
Effect of Polycyclic Aromatic Hydrocarbons (PAHs) on Modulate Genes Encoding Stress Related Proteins and Antioxidant Enzymes in Different Marine Fish Species of Red Sea Water
No full textPolycyclic aromatic hydrocarbons (PAHs) in the Red sea water were determined at Suez and Ismailia
governorates, Egypt. The sites were selected to represent areas with different activities of Suez Gulf water.
The concentrations of fifteen PAHs having two to six rings were determined by using HPLC with florescence
detection. The total average concentrations of the fifteen PAHs over the Suez governorate sites (S1 and S2)
were 1.45 and 0.34 ??g/l, respectively. However those for Ismailia governorate sites (I1 and I2) were 1.06 and 0.24
??g/l, respectively. PAHs having four to six rings were the predominant compounds in particulate matters.
The major sources of PAHs and their impacts on the health of certain types of fish such as Mullet and Sea-bass
species were studied through the effect on the expression of stress protein related genes. In addition,
expression of stress protein related genes (Cytochrome P450, CYP1A and metallothionein, MT-1A) and
antioxidant enzymes (Glutathione-S-Transferase and GST alpha) in liver tissues of Mullet and Sea-bass
collected from studied locations in Ismailia governorate and Suez gulf were assessed. The results revealed
alterations in the hepatic mRNA levels of CYP1A, MT-A and GST alpha genes in Mullet and Sea-bass collected
from S1 location at Suez gulf compared with I1 location at Ismailia governorate and with the S2 and I2 locations
as reference site. The current findings suggest that the genes encoding stress related proteins and antioxidant
enzymes studied in this paper represent valid biomarkers to detect variation of fish stress conditions attributed
to PAHs
The prevention impact of the green algal extract against genetic toxicity and antioxidant enzyme alteration in the Mozambique tilapia
No full textAlgal studies are primary for ecological risk assessment and toxicology by evaluating lethal and sub-lethal toxic impacts of potential toxicants on inhabitants of numerous ecosystems. Dunaliella salina, a green marine alga, is characterized by its carotenoid accumulation and is widely used in many health and nutritional products. Our experiment was designed to evaluate algal extract's ability to inhibit genetic alterations induced by mutagen agents such as dioxin in the Mozambique tilapia. The expression of three stress genes was examined: heat shock protein 90 (Hsp90), CYP1A1 as one of the main cytochrome P450 enzymes, and metallothionein (MT). The study exhibited a characteristic sensitivity to metal treatments. Liver samples were collected from all fish to analyze bio-indicators, including superoxide dismutase (SOD), malondialdehyde (MDA), and reactive oxygen species (ROS). While gills samples were used for DNA fragmentation assay. Results showed that oxidative stress in the dioxin group's liver significantly changed indicators. However, the dioxin group significantly increased the SOD, MDA enzyme activities, and ROS formation. Interestingly, the genes Hsp90, CYP1A1, and MT expression were significantly down-regulated in Dunaliella salina groups. Nevertheless, DNA fragmentation in gill organs was affected by exposure to dioxin in fish. Thus, it was concluded that the methanolic extract of an isolated strain Dunaliella salina is effective against mutagen agent dioxin by inhibiting genetic alterations in fish organs with an antioxidant defense system to conquer oxidative damage
The Duckweed, Lemna minor Modulates Heavy Metal-Induced Oxidative Stress in the Nile Tilapia, Oreochromis niloticus
No full textA two-fold integrated research study was conducted; firstly, to understand the effects of copper (Cu) and zinc (Zn) on the growth and oxidative stress in Nile tilapia, Oreochromis niloticus; secondly, to study the beneficial effects of the duckweed Lemna minor L. as a heavy metal remover in wastewater. Experiments were conducted in mesocosms with and without duckweed. Tilapia fingerlings were exposed to Cu (0.004 and 0.02 mg L−1) and Zn (0.5 and 1.5 mg L−1) and fish fed for four weeks. We evaluated the fish growth performance, the hepatic DNA structure using comet assay, the expression of antioxidative genes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx and glutathione-S-transferase, GST) and GPx and GST enzymatic activity. The results showed that Zn exhibited more pronounced toxic effects than Cu. A low dose of Cu did not influence the growth whereas higher doses of Cu and Zn significantly reduced the growth rate of tilapia compared to the control, but the addition of duckweed prevented weight loss. Furthermore, in the presence of a high dose of Cu and Zn, DNA damage decreased, antioxidant gene expressions and enzymatic activities increased. In conclusion, the results suggest that duckweed and Nile tilapia can be suitable candidates in metal remediation wastewater assessment programs
Application of SMA fiber composite as seismic reinforcement for concrete moment resisting frames
No full textFor many years, steel has been used as the primary reinforcing material for concrete structures. Despite requisite stiffness, strength, ductility and desired deflection properties, steel reinforcing bars have tendency to incur permanent plastic deformations under excessive loading. Recently, fiber reinforced polymer (FRP) reinforcing bars have also been used in concrete structures to address corrosion issues typically associated with conventional steel bars. However, due to their linear elastic behavior, they are not considered in structures which require ductility and damping characteristics. The use of shape memory alloys (SMAs) with their nonlinear-elastic behavior in the composite could potentially provide solution for this problem. Small diameter super-elastic Nickel-Titanium (NiTi) SMA wires, coupled with polymer matrix is sought in this research as reinforcing bars in reinforced concrete (RC) moment resisting frames (MRFs) to improve the performance of the frames in terms of reducing residual inter-story drifts and damage under earthquake loading, while still maintaining the elastic characteristics associated with FRP. SMA fibers, conventional polymeric fibers and resin are infused together to manufacture the new composite under high pressure and temperature. Uni-axial cyclic tensile tests are carried out to characterize the mechanical hysteretic behavior of the new composite. Analytical constitutive models are developed for the SMA-based composite materials and calibrated based on experimental test results. These material models are then extended for use in structural models to capture the hysteretic behavior of the composite. The new SMA composite reinforcement is placed at the plastic hinge region of the MRFs, where most of the damage is expected. RC MRF prototype structures reinforced with steel, SMA-FRP and conventional glass-FRP (GFRP) composite reinforcement are designed using two different approaches involving equivalent static force procedure and capacity spectrum method. Multiple non-linear time history analyses are conducted using incremental dynamic technique for assessing the performance of the MRFs under suite of ground motions. Main shock-aftershock ground motion sequences are utilized to examine the efficacy of using SMA-FRP composite in plastic hinge zones of MRFs. Damage assessment is performed based on residual inter-story drift and drift performance levels. Efficacy of proposed SMA-FRP composite reinforcement is further explored by embedding it in a small scale beam tested under 3-point bending.Item withdrawn by Mark Zulauf ([email protected]) on 2013-04-17T20:23:49Z
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Treatment of multiple sclerosis in special populations: The case of refugees
No full textMultiple sclerosis was long considered a relatively rare entity in the Middle East, but research over the past 10 years and the publication of the Middle East North Africa Committee for Treatment and Research in Multiple Sclerosis guidelines for multiple sclerosis have allowed diagnosis and treatment to occur more efficiently. Most of the first and second-line disease-modifying therapies approved by the Food and Drug Administration and the European Medicine Agency are available in the Middle East. However, the availability of disease-modifying therapies is quite variable, with some countries having access to all multiple sclerosis disease-modifying therapies, while in others there is only one therapeutic option. Economic limitations remain a challenge for the management of multiple sclerosis, especially in countries of war. Moreover, the burden of multiple sclerosis treatment in Syrian and Palestinian refugees is likely high due to the non-availability of funds to cover the high cost of disease-modifying therapies. © The Author(s) 2020
Evaluation of Mitigation Role of L-Phenylalanine-Based Low-Molecular-Weight Gelator against Oil Pollution-Induced Nile Tilapia Toxicity
No full textA lot of oil is leaked into aquatic environments, significantly impacting fish health and, consequently, human populations. This study aimed to introduce an L-phenylalanine-based low-molecular-weight gelator (expressed as Z-Phe-C18) as a smart remediation tool for oil spills. Several groups of Nile tilapia were allocated in aquaria exposed to different doses of crude engine oil with/without the organogelator for 4 weeks. The results revealed a significant increase in biochemical oxygen demand, chemical oxygen demand, electrical conductivity, and total dissolved solids in water samples of fish aquaria exposed to oil pollution. The antioxidant activity levels, micronucleus formation, and expression patterns of stress-related genes were significantly higher in the livers of fish exposed to crude oil than in those of control fish. On the contrary, fish groups exposed to oil pollution and treated with the organogelator indicated that antioxidant enzymes, micronucleus incidence, and gene expression alteration of stress-related genes declined compared with those exposed to oil pollution only. The results suggest that oil pollution can induce oxidative stress via the enhancement of oxygen free radical formation. On the contrary, oil removal by the organogelator decreases oxidative stress and consequently strengthens fish immunity. So, we can conclude that organogelator treatment is promoting oxidative resistance development by increasing the activities of antioxidant enzymes, which are important in protection against oil pollution and preventing peroxidation of fish tissues. Promisingly, the organogelator could be used as a tool for the remediation of oil pollution in aquatic environments
Grading reflective essays: The reliability of a newly developed tool- GRE-9
No full textBackground: The main objective of this study is the development of a short reliable easy-to-use assessment tool in the aim of providing feedback to the reflective writings of medical students and residents. Methods: This study took place in a major tertiary academic medical center in Beirut, Lebanon. Seventy-seven reflective essays written by 18 residents in the department of Family Medicine at the American University of Beirut Medical Center (AUBMC) were graded by 3 raters using the newly developed scale to assess the scale reliability. Following a comprehensive search and analysis of the literature, and based on their experience in reflective grading, the authors developed a concise 9-item scale to grade reflective essays through repeated cycles of development and analysis as well as the determination of the inter-rater reliability (IRR) using intra-class correlation coefficients (ICC) and Krippendorff's Alpha. Results: The inter-rater reliability of the new scale ranges from moderate to substantial with ICC of 0.78, 95% CI 0.64-0.86, p < 0.01 and Krippendorff's Alpha was 0.49. Conclusions: The newly developed scale, GRE-9, is a short, concise, easy-to-use reliable grading tool for reflective essays that has demonstrated moderate to substantial inter-rater reliability. This will enable raters to objectively grade reflective essays and provide informed feedback to residents and students. © 2020 The Author(s)
Efficient spectrum availability information recovery for wideband dsa networks: A weighted compressive sampling approach
No full textThere have recently been research efforts that leverage compressive sampling to enable wideband spectrum sensing recovery at sub-Nyquist rates. These efforts consider homogenous wideband spectrum, where all bands are assumed to have similar primary user traffic characteristics. In practice, however, wideband spectrum is not homogeneous, in that different bands could present different occupancy patterns. In fact, applications of similar types are often assigned spectrum bands within the same block, dictating that wideband spectrum is indeed heterogeneous. In this paper, we consider heterogeneous wideband spectrum and exploit its inherent block-like structure to design efficient compressive spectrum sensing techniques that are well suited for heterogeneous wideband spectrum. We propose a weighted ?(1) -minimization sensing information recovery algorithm that achieves more stable recovery than that achieved by existing approaches, while accounting for the variations of spectrum occupancy across both the time and frequency dimensions. In addition, we show that our proposed algorithm requires a smaller number of sensing measurements when compared to the state-of-the-art approaches.Manuscript received December 6, 2016; revised June 6, 2017, September 27, 2017, and November 30, 2017; accepted December 26, 2017. Date of publication January 9, 2018; date of current version April 8, 2018. This work was supported in part by the U.S. National Science Foundation through the NSF Award under Grant CNS-1162296. The associate editor coordinating the review of this paper and approving it for publication was X. Zhou. (Corresponding author: Bassem Khalfi.) B. Khalfi and B. Hamdaoui are with the School of EECS, Oregon State University, Corvallis, OR 97331 USA (e-mail: [email protected]).Scopu
